Quarterly report pursuant to Section 13 or 15(d)

- Eastern Interconnect Project (Details)

v3.3.0.814
- Eastern Interconnect Project (Details)
 3 Months Ended 9 Months Ended
Sep. 30, 2015
USD ($)
Sep. 30, 2014
USD ($)
Sep. 30, 2015
USD ($)
kV
mi
Sep. 30, 2014
USD ($)
Oct. 31, 2012
Eastern Interconnect Project [Member]          
Sale Leaseback Transaction [Line Items]          
Length of transmission lines physical assets | mi     216    
Power of transmission lines physical assets | kV     345    
Estimated useful lives of assets     20 years    
Amount of depreciation of leased property $ 0 $ 570,000 $ 570,000 $ 1,700,000  
Public Service Company of New Mexico [Member]          
Sale Leaseback Transaction [Line Items]          
Business Acquisition, Percentage of Voting Interests Acquired         40.00%
Lease Expiration Date     Apr. 01, 2015    
Future Expectations [Member] | Public Service Company of New Mexico [Member]          
Sale Leaseback Transaction [Line Items]          
Fair Value of Lease Option Under Agreement $ 7,700,000   $ 7,700,000